1. Field of the Invention
The invention involves an electronic device capable of interacting with electronic identification and/or transaction devices, called here generically xe2x80x9cbadgesxe2x80x9d.
2. Discussion of the Background
Different types of badges are currently used, in various forms, as means of identification and/or for carrying out a transaction. xe2x80x9cTransactionxe2x80x9d is understood to mean here any operation aiming to validate any right, whether this consists of a right of access that is physical (a toll, for example) or immaterial (access to information), or a right to give and/or receive any benefit, whether monetary or not, in relation to a service, whatever the nature of the service may be.
The badges most widely used at present are memory cards, the majority of which interact with a reader through an electronic connection. Different proposals with the aim of reading the badge, and writing on it if necessary being carried out without contact, have emerged. But the diversity of these proposals runs counter to standardization, and consequently to the development of badges that are readable without contact; the practical relevance of these is, however, undeniable.
In addition, in the absence of physical contact, there is a risk of interference between several co-existing contactless connections that are initiated at the same time, for example between two badges and a single contactless reader, or between two badges and two contactless readers next to one another.
It is therefore desirable to develop a contactless reader that is sturdy, has low additional costs, is not very sensitive to interference, and is versatile, while performing comparably to readers already in use.
The Applicant was confronted with this problem.
The current invention provides a structure for a contactless reader that improves the situation appreciably.
The contactless badge reader proposed is of the type including transmission means and reception means, working more or less on the same carrier frequency, and linked by a coupling circuit to an antenna; it also includes management means, which interact with the transmission means and reception means to establish a dialogue with a badge.
The main characteristic of the invention is that the coupling circuit to the antenna includes a delay element, crossed by the connection between the transmission means and the antenna; the reception means comprise two channels, beginning on either side of this delay element; and the management means are arranged to make use of the reception channels selectively, according to a chosen criterion, in particular selecting one of the reception channels according to a chosen criterion.
An advantage is that the delay of the delay element is more or less equal to an eighth of the wavelength of the carrier frequency, up to close to a complete number of half-wavelengths. In one specific instance, the delay element includes a capacitor.
Another aspect of the invention is that the coupling circuit to the antenna operates at low impedance.